Incandescent lamp



Feb. zo, 1940. K, L, WADE 2,191,189

INCANDESCNT LAMP Filed Oct.' 12, 1937 5 Sheets-Sheet 2 ATTORNEY Feb. 2o, 1940.

K. lr.. WADE INCANDES CENT LAMP Filed Oct. 12, 1957 5 Sheets-Sheet 3` N0N.,Lumi/warum ONS HUM/MATIN@ ZONE ATTORNEY Patente-d Feb. 20, 1940 oFFicl-z INCANDESCENTLAMP i Kenneth L. Wade, New York, N. Y.

Application october 12,

7 Claims.

This invention primarily relates to improvements in an incandescent lamp and more particularly to improvements designed to make such a lamp more efficient and economical. The principal features of the improvements are embodied in the filament and in provisions for reflecting light rays and cleaning the gas currents inside an incandescent lamp' ofthe vaporized particles of the filament whichwould otherwisesoil the `lamp globe.

p Specifically fabrication and use of a filament having a grooved surface to reduce the `losses from filament evaporation andtoincrease the efciency of such a filament as much as possible by 'the use of grooves. `Another contemplated improvement is the provision of a filter means to take out of the gas currents inside of a lamp the evaporated particles of the filament which are cari ried away by such currents and may be deposited on and stain the globe. Still another feature is a reflector `so placed as to redirect those light rays from the filament which are originally headed towards the non-illuminating areas of the lamp; The desirability of these improvements immediately becomes apparent to those `familiar with the problems of theart.

`Present day incandescent lamps are usually `provided with a round tungsten wire filament.

It haslong been known that tungsten particles vaporized from the filament, causing a proportionate decrease in theI size of thefilamentand normally also in the efficiency and life of theA lamp.` Further it Was known that this action,

' whilesomewhat retarded by the surrounding gas in a gas-filled lamp, still took place in sufficient measureto be the source of a brown deposit.

knows. The use of a grooved filament in lamps i such as radio and X-ray tubes where electron" emission filaments perform with its concomitant advantagesl hereinafter set forth, also is as yet unknown to the tube industry.`

In a preferred embodiment, the new filament is grooved lengthwise at spaced intervals around its periphery. In cross section such a filament this invention contemplates the 1937, seran No. 168,531

(o1. 17e-'Aw' m m p p resembles a toothed gear in side elevation and by means of these grooves the normal evaporaof the `respective grooves, but the result achievedv is a lampl filament having greater efficiency and a longer life than the corresponding standard filament inuse today. Similar benefits are obtained by using a Viilarnent of this type in` any application of an` incandescent filament, such as in the electron emission filaments of/radio and 'X-ray tubes, Where present day performance Would be materially advancedby a reduction in evaporation loss of the filament. In a similar fashion the grooves on the surface of the filament will produce areas of `heat concentration where the heat rays are inter-` cepted bythe sides thereof. The inventor believes that suchconcentration will produce from `a tungsten filament of this invention more light rays in the visible spectrum than a corresponding standard tungsten filament.

Most lampsare gas-filled and the heating of such gas in proximity to the filament produces `convection currents carrying away some portion of Whatever particles are vaporized from the filament. These particles ofttimes `deposit on the globe in the illumination areas in the form of a brown deposit (fortungsten filaments) so that the positioning of a filter inthe path of such currents to cut down the brown deposit is of considerable benefit. True, ythe deposit would be made on the filter instead, which in one of the described forms is made of glass wool, but since -such a filter is placed in a position outside of the illumination zone,y its effect would be verymarked in keeping the currents and consequently the globeclean. As forthe light `rays Which head towards `the non-illuminating zone of the lamp, part of thisinvention isl a mirrorlike device which bends, such rays around and into the proper directions. Usually this device p will be in the'form of a small concave reflector placed adjacent the filament in the non-illumination region. i

. It is an object of this invention `to produce a filament to be heated to incandescence suitable foriuse in an incandescent lamp, and X-ray or radio tube, characterized by a series of grooves in its periphery. l

It is an object of `this invention to produce a longer lasting and more efficient incandescent lamp by the fabrication and use therein of a filail, l)

ment grooved substantially in a lengthwise direction.

It is another object of this` invention toretard the normal deposit of vaporized particles of a larnent on the inside of the globe of `such a lamp by the interposition of a filter in the path of flow of such particles.

It is still another object of this invention to Other objects, advantages `and features will be had from a study of the balance of this specification and the accompanying drawings; in

which: l j

Fig. l is a view in elevationv of an incandescent lamp utilizing the iilament of this `invention;

Fig. isl an enlarged view of two loops of a lilament coil embodying a preferred form of this invention;

Fig. 3 is an enlarged view in cross-section ci the filament of Fig. 2;

Figs. 4 'to G inclusive, are fragmentaryY crosssectional views of different contours which the grooves in the lament of 'this invention may have; v

Fig. 'l isacross-section view of a die forone form of the iilament of this invention;

Fig. 8 is a plan viewof an incandescent lamp,v

partly yin cross-section, showing one form` oi' the `filter of this'inventicn forv cleansing the convection currents of brown deposit;

Fig. 9 is a lplan view of the filter assembled in Fig'. l0 is similar to Fig, 8, but showing a modified forni ofsuch a filter;

- Fig. ll is a lplan vievvcf the filter assembled in Fig. 10;

Fig. l2 is` an incandescent lamp` showing one "form of the reflector of this invention for redirecting light rays;

Fig. 13,is` an enlarged View oi the reflector of Fig. lZand adjacent parts; and

Fig. li is a modified form of such a reflector mounted in a lamp. y

Referringto the drawings, lll and ll respectively are the globe andv base vof anincandescent lamp. However, this lamp contains the filament i2 which is a i'eature of this invention, mounted upon the usual supports it and connected to the base by the usual leads it. Filament l2 preferably is coiled and is grcoved (Fig. 2) lengthwise at spaced intervals so that in cros -section it appears sl'ic'wnin Fig. 3. For better depiction the scale for the 'iilaxncnt details is oversize.

When ilament kl2 is heated to incandescence the normal evaporation loss of particles of filament material, generally tungsten, is arrested to a great degree by coming in Contact with the `side ol' the groove oppositejto the side or surface oi particle origin whereuponthe particle. adheres to vsuch opposite side and the normal loss by vaporization which reduces the filament is materially lessened.

The probable explanation is that such vaporization takes place normally te the surface and with the grooved lanient practically all of' the nia--` ment surface is composed of the sides of the grooves, particles from one surface will be blocked by the other surface oi each groove where they will adhere and `vice versa.y

Light and heat rays emanate from the filament surfaces perpendicular thereto-similar to the explanation olfered'regarding the path of vaporv ized particles-and in like fashion impinge on the opposite wall whence the bombardment raises the surface temperature in the grooves. Such heat concentration reduces cooling losses and also quite possibly contributes to the increase in the efficiency of a lamp with the lament of this invention by contributing' to a rise in the temperature of the iilament and hence to an increase in the light emission therefrom. The sum total of the advantages of using such ay lament result's in a lamp having a greater efficiency through a rated life or a longer life or both.

Illustrated in Figs. 5 and 6 are `differently shaped grooves, I5 and IE, Whichmay be employed Without departing from the scope of the invention. In fact, While the preferred embodiment of filament i2'is grooved parallelwise toits longitudinal axis, such grooving can be inthe iorm of a broken or continuous helix and will produce the advantages of this invention in the way of particle blocking and increased efficiency. liicr is the use oi" such a iilament restricted to incandescent lamps since it may also be used with prci'itin radioand X-ray tubes Where electron emission by` the filament is the iilarnents made of tungsten carbide Aor diamond and itsy use Will result in an economically produced tungsten filamentsimilar to filament l2.

ln the incandescent lamp disclosed in Fig. 8,

2li is the globe and 2E is the base thereof. Inside the'lamp are filament 22 with the usual app-un` tenances and a filter 23. Filter 23 comprises an annular retainer 24 andthe filter material 25. The lower portion i9 of the'annular retainer i4- shown'in more detail in Fig. 9-is concave and silvered so that it has a dual function' being'a' reflector and part of a lter.. The functicnrof reflector portion i9 is explained more fully `in connection with the reflectors shown in Figs. l2 teil4. Material 25, asfshown,l comprises glass wool or yarn wound in fiat nest form around the .stem 26 adjacent retainer 24 which serves to give it the needed stability. In operation the iilament heat sets up convection currents in the gas inside of globe 2t. These currents, graphically indicated 'by arrows in Fig; 8, vvcarry whatever vaporized tungstenparticles escape from the filament 22 through suitable periorations 2l in retainer 24 and deposit such particles on the iilter `material 25. By these means the inside of'globe 20 remains imsoiledbecause the gases coming in contactl therewith have been previously cleanedby iilter 23. The lter is always placed above the iilament as shown in Fig. 8 with a"baseup lamp. Even with a base-dovvn. lamp, a similar lter can be used although it would likely be smaller and closer to the lament.

The lamp of Fig. l comprises a globe 3ll`and a base 3l. The lament 32 is supported on a stem 33 and integral with said stem is aset vof spider# like .arms 3d between which lter` material 35 is wound. `In operation the filter 36 operates pre# cisely as does iilter 25 (Fig. 8) but freer passage for convection currents is afforded by arms 34 than by reflector retainer 24 which is only perforated (Fig. 9). In.- assembling these filtersthe nlter materialv in iinal position is squeezedy into the lamp and afterwards any temporary disarrangement is corrected.

s 40 is a globe and 4I a base on the lamp illustrated in Fig. 12. Filament 44 is supported by means of filament supports 43 and leads`45 suitably anchored in stem 42. Positioned on stem 42 adjacent filament ill is `a concave reector 46.

\ In the enlarged view thereof in Fig. 13, reflector 46 is shown composed of a glass base 41 and siland the larnent 44 forms `an illuminating zone` for the purposes of this description. Naturally the better the reflector the more light `is redirected and the greater the saving. In assembling rellector 46 is aflixed in place over the enlarged end of stem 42.

In the modied rellector` 49 shown in Fig. 14,`

the distance between thefllament 50 `and reflector 49 determines,` as shown, the boundaries between illuminating zone and area and the` contra state.

Shifting reflector 49 on stem 5l before the lamp is assembled changes such boundaries accordingly. s

This application is not limited by the theories expressed herein to explain the benecial results obtained nor is the invention of any narrower scope than that defined by the following claims.

The subject matterdescribed but not claimed herein is covered by my copending application S. N. 314,227 led January 17, 1940.

I claim: y l

1`. A drawn metallic lament having a grooved surface, said surface comprising substantially contiguous grooves and said grooves comprising side surfaces substantially formingv contiguous acute angles of approximately 25 degrees.

2. A drawn metallic filament having a series of contiguous grooves `running lengthwise on its surface, each of said grooves being approximately an equally angled acute angle of not less than 15 degrees and not more than 40 degrees.

3. Anincandescent filament of a generally circular cross section having a series of acute angled grooves on its surface whereby lament vaporization is retarded, greater surface area is provided and multiple reflection of rays emanating from the sides of said grooves is obtained.

4. An incandescent lamp lament of a gener-A ally circular cross section having a series of grooves on its surface, the sides `of each `such groove `forming anangle of substantially 25 degrecs, i

5. A filament having a series of surface grooves substantially involute in cross section around its periphery.

6. An incandescent4 lament having a grooved surface, said surface comprising substantially `contiguous grooves and said grooves comprising side Asurfaces substantially forming contiguous acute angles. i

7. A tungsten lament having a series of adjacent grooves running lengthwise on its surface, the sides of each such groove forming an angle of 90 degrees or less. v

` KENNETH L. WADE. 

